The Norseal Norsound NOR720 is a discreet kerf-fit acoustic and smoke door seal designed to provide an effective seal around timber doorsets without the need for a surface-mounted profile.
Manufactured from flexible TPE (thermoplastic elastomer), the NOR720 is fitted into a narrow machined groove or kerf within the door or frame. Its flexible sealing fins compress or deflect when the door closes, helping to reduce gaps through which airborne sound and ambient-temperature smoke can pass.
The NOR720 is suitable for installation around the head and jambs of smoke-control doorsets and can also be used at the meeting stile of acoustic doorsets. This makes it particularly useful where acoustic or smoke-control performance is required while maintaining a neat and unobtrusive appearance.
The seal has been smoke tested in accordance with BS 476-31.1 and acoustically tested in accordance with BS EN ISO 10140-2, making it a strong choice for commercial, residential, hospitality, healthcare, educational and public-building applications where effective perimeter sealing is important.
Key Features & Benefits
- High-performance acoustic and smoke door seal
- Kerf-fit design for a neat and discreet installation
- Suitable around the head and jambs of smoke-control doorsets
- Suitable for the meeting stile of acoustic doorsets
- Helps reduce the transmission of airborne sound through perimeter gaps
- Helps restrict the passage of ambient-temperature smoke
- Manufactured from flexible and durable TPE
- Acoustically tested in accordance with BS EN ISO 10140-2
- Smoke tested in accordance with BS 476-31.1
- Compact 5 × 4.2 mm profile
- Available in 2100 mm and 3000 mm lengths
- Available in Black, Brown and White
- Other lengths may be available subject to manufacturer availability
Where is the NOR720 Used?
The NOR720 is designed primarily for use with timber acoustic and smoke-control doorsets and is suitable for applications such as:
- Hotels and guest accommodation
- Apartment and residential developments
- Offices and meeting rooms
- Schools and universities
- Hospitals and healthcare facilities
- Public buildings
- Commercial developments
- Conference and meeting facilities
- Rooms requiring increased acoustic privacy
On acoustic doorsets, sealing the gaps around the door leaf is particularly important. Even small uncontrolled air gaps can provide a path for airborne sound, so perimeter, meeting-stile and threshold seals should be considered as part of the complete acoustic doorset specification.
Kerf-Fit Installation
Unlike a self-adhesive surface-mounted door seal, the NOR720 is installed into a machined groove or kerf, resulting in a particularly neat finished appearance.
Norseal's installation guidance specifies a kerf approximately 3 mm wide × 4 mm deep, with the NOR720 pressed securely into the prepared groove. At corners, the seal should be cut at approximately 45° to maintain a continuous perimeter seal.
When installed adjacent to a door stop, Norseal recommends that the seal overlaps the stop by approximately 0.5–1 mm to achieve the required compression when the door closes.
Installation should always be carried out in accordance with the manufacturer's current fitting instructions and the requirements of the particular doorset.
Can the NOR720 Be Used at the Bottom of a Door?
Yes. Norseal's fitting instructions also state that the NOR720 can be used as a door-bottom seal when combined with a suitable threshold plate. For this arrangement, Norseal specifies a floor-to-door-bottom gap of approximately 7–9 mm.
For higher-performance acoustic doorsets, a dedicated automatic drop seal may offer a more appropriate threshold-sealing solution depending on the required acoustic performance and doorset specification.
Technical Information
Product: Norsound NOR720
Manufacturer: Norseal
Product Type: Kerf-fit acoustic and smoke seal
Application: Head and jambs of smoke-control doorsets / meeting stiles of acoustic doorsets
Fixing: Kerf-fit / rebated
Material: TPE
Profile Size: 5 × 4.2 mm
Standard Lengths: 2100 mm and 3000 mm
Colours: Black, Brown and White
Smoke Testing: BS 476-31.1
Acoustic Testing: BS EN ISO 10140-2
NOR720 vs NOR710 – What's the Difference?
Both the Norseal NOR720 and NOR710 are designed to improve acoustic and smoke sealing around doors, but their method of installation is different.
The NOR720 is a kerf-fit seal, meaning that it is inserted into a narrow groove machined into the door or frame. This produces a very neat installation and is particularly suited to doorsets where the seal can be incorporated during manufacture or machining.
The NOR710 is self-adhesive and surface mounted, making it particularly useful for retrofit installations where machining the existing door or frame is undesirable.
The most appropriate seal should therefore be selected according to the doorset design, required performance and method of installation.
Why Choose the Norseal NOR720?
The effectiveness of an acoustic or smoke-control doorset depends heavily on controlling gaps around the door leaf. The Norsound NOR720 kerf-fit door seal provides a compact and discreet means of sealing these gaps while maintaining low visual impact on the finished doorset.
Its combination of acoustic testing, smoke-control performance, compact dimensions and concealed kerf-fit installation makes it particularly suitable for professionally manufactured timber doorsets and specification-led projects.
